How to exchange data between page and page part?


On Microsofts documentation here it says "Parts can either represent self-contained functionality, or can be contextual and exchange information with the hosting page."

It is not clear to me how to exchange data between hosting page and hosted page part

Note: I am aware of subpagelink and subpageview properties but those don't solve my problem

Lets say i have a page of type list that given an "item category" shows its "item attributes"

After choosing an "item attribute value" for each "item attribute" (from the main page) i want to filter a page part that is basically an "Item" list so that it shows only items that have the same "item attribute values" selected on the hosting page.

Can anybody give me a clue on how to do this?